MICROANGIOGRAPHY IN EXPERIMENTAL CEREBRAL EDEMA IN RATS.

Abstract

While microradiography was employed as early as 1913 by Pierre Goby, the first attempts at its use in the demonstration of minute blood vessels in animals were made in 1935 (Grechiskin-Prives, in Leningrad), withThorotrast (1). The effects produced in the brain and spinal cord of animals by chronic intoxication with alkyl tin compounds, specifically triethyl tin hydroxide and sulfate, have been described in detail by several authors. Stoner et al. (19) and Magee et al. (13) investigated the edematous changes in the central nervous system of rats by light microscopy, and later Torack, Terry, and Zimmerman (20) reported the alterations in the brain as seen by electron microscopy. As described by these investigators, progressive neurological deterioration was observed with decreased activity, and paralysis of the hind limbs and later of the fore limbs and weight loss due to low food intake were apparent. Within a period of three weeks generalized rigidity and coma developed. The histologic changes in edema induced in the brain by numerous methods have been the subject of detailed studies (5, 8, 9, 21, 22). These variations are characterized in the main by three factors; edema of the glial cell bodies and processes (11, 20), dilatation of the perivascular spaces, and interstitial accumulation of fluid (8, 9, 11, 13, 15, 17, 21). It is the purpose of the present report to analyze the angiographic alterations in the brains of rats with cerebral edema and to correlate them with microscopic sections stained with hematoxylin-eosin. Since it is the general consensus that swelling and edema represent varying degrees of the same process (5, 11, 15, 17, 18, 22), the terms will be used interchangeably in this discussion. Method To determine the normal microradiographic appearance of the cerebral vessels, a control group of 20 albino rats (weight, 175 to 200 gm.) was studied. Following the technic outlined by Chang and Trembly (4) and Margulis et al. (14), the rats were anesthetized with an intraperitoneal injection of 18 mg. of sodium pentobarbital. After thoracotomy a small PE-160 polyethylene catheter was inserted into the left ventricle and, while the animal was still alive, approximately 10 ml. of a mixture of 3 to 1 Micropaque2 and Thorotrast3 was injected by hand. The injection pressure never exceeded 120 mm. of mercury. The animal always died during the injection, when the entire arterial tree was filled with the contrast material. The brain was then removed by craniotomy and fixed in 10 per cent formalin. One-millimeter sections were used to obtain microangiographic slides according to the method described by Chang and Trembly, and McAlister et al. (12) on Kodak spectroscopic plates. The slides were studied under the microscope. In the second group, 40 albino rats of about the same weight were fed powdered food and water mixed with a solution of 20 parts per million of triethyl tin hydroxide4.